Vulcanization of rubber



Patented Nov. 4, 1930 ,wm m score or 1mm LABORATORIES ooMrAnY, or AKRON,

11o Drawing.

WEST VIRGINIA,- Assronon 'ro urns RUBBER. s nvIcE 01110, A CORPORATION or 01110 vULcAnIzArIon 3113313 f i The "presentinvention relates to the manufacture of a Vulcanized rubber productby an improved process employed as an accelerator of that process. The-invention willbe understood from the following description and exampleswherem the invention is fully set forthand described; Various guanidine derivatives heretofore have been. described as rubber vulcanization accelerators. The guamdines most efiectlve for use for that purpose, however, have'commaterially increased by substituting in one of.

, havealso beenfo'und to possess valuable rub? prised such symmetrical compounds as-dihenyl-guanidine, di-o-tolyl-guanidine and the like. It has now been found that the accelerating power of thesecompounds can be the aryl groups in place of a hydrogen inthe para position to one of the imido-groups of a di substitut ed. guanidine, apiperidine'. nucleus, whereby products such asan aryl-p-piperi-dyl-aryl guanidine are produced. in ;Simirlaricompounds in which the group is substituted'in an ortho position,.and mixtures of the orthoand para substituted compounds ber vulcanization accelerating properties. Y Although thepreferred class .of accelerating compounds maybe manufactured by any of several different processes, one satisfactory mode of'obtaining a mixture of an arylortho and an aryl-para pip'eridyl-phenylguanidineis shown by the: following examp1e.-: Chlor benzene wasnitrated in the usual mannerand a product was obtained comprising'a mixture of approximately of the ortho and 7 0%,of the para-nitro-chlor benzenes. This mixture wasthen reacted with piperidine whereby a mixture of the corr'e spondingortho and p ra substituted piperi dyl-nitrobenzenes was obtained, jj The jm ix-f ture of the nitro bodies was then'i'educedlby means-0f iron and'hydrochloric acid andthe 7 corresponding substituted; amino xbenzenes I a were obtained. The mixture ,of substituted 0- and p-amino benzenes was thenreacted with a mustard oil, preferably withfiphenyl mustard oil, whereby ;a mixture of phenyl-p- Application filed November 28,1927. sr'iai no. 236373;

wherein an unsymmetrically substituted 'guanidine 1 compound 1s n l'.- yo iperidyl'- phenyl i thioureas was obtained ,inthe proportion of approximately/% of the formerand 30% of'the latter. .v

The thioureasfwere then desulphurized and amidated by, treatment with lead oxide 7 in the vpresence of ammonia and the corresponding guanidines were obtained. Other means of manufacturingthe preferred type of Iaccelerating compounds are possible. 1 Thus, an equi-molar mixture of aniline with the ortho or para. or with a mixture of 0- and p-piperi-i dyl-aniline would ,yield a" mixed "th'ioure'a upon treatment with carbon bisulfid. "The thiourea would-then be desulphurized and amidated in the well known manner for car rying out these steps. q o 1 Another method ,of manufacturing the guanidine compound comprises the produc; tionof the "hydrochloride of the mixed guanidine by theaction of cyanogen chloride on :anequi-molarfmixture of aniline and -p-piperidyl-aniline; The free guanidine is read:

ily obtained by treating asolution of the hydrochloride'withcaustic soda solution in sufficient quantity to neutralize the acid.

Other: guanidine compounds analogous I to i the one particularly .set forth in the example can readily be obtained bylemploying homo I 'l'o guesof aniline, such as the toluidines, the xylidenes or other aromatic primary amines in place of anilineset'forthl Ina like man ner, alkylsubstituted chlor benzenes and.

other aryl mustard oils than jphenylmustard oil can be employed in;place: of the specific compounds mentioned i in: the various processes for manufacturinglthe desired compound: I. v i a a effective rubber vulcanization accelerators.

- Thus, a rubbercomposition comprising 7 ldoparts ofpale crepejrubber, I j 15*partsof zinc'-oxide, 3.5' p'artsof sulphur,

1 of accelerator, was prepared in the-well known manner-f l an -accelerator there was employed. in

'aryl e p a ryl-J guanidines A ,have been-[found to ;comprise"-,a class of" one example phenyl-p-piperidyl-phenyl-guanidine having the formula CHI-CH1 0m 3 Modulus'of elasticity 7 Y 7 elongatwns of Tensile Ultimate Accelerator used strength elonga- I at break .tion

DiphganyI-guanidine- 140 v 250 857 2325 870% Phenyl -p piperidy1- r phenyl guenidine... 177 '357 1320 3310 885% From'the table it is evident that the'preferred class of'accelerators produce a cured rubber compound possessing a tensile strength that is approximately greater than that yielded by the use of di-phenyh guanidine when employedas a vulcanization accelerator inua rubber stock of the same composition: Longer times of cure produce a stock with hi'gh'er modulus and tensile figures, but the example given illustrates the value of'the accelerator in a so-called pure gum stock.

1 The preferred class of accelerators has also been -foun dito be :desirable and effective for i'use in rubber stocks employed in tire treads as is shown by the following-example; :A tread stock was compounded in the well known'manner comprising I 36,5 partso f smoked sheet rubber,

O parts-'o'famber crepe'rubber, 11 parts of zinc oxide, 25 partscarbon black,

*31'5 partso'f mineral rubber,

1 part of cycline oil,

2- partsof sulphur,

nyl-p-piperidyl phenyI-guanidine.

stock, vulcanized as described, are as follows:

5-part of accelerator, for example phe- Mfdllllfi) oaelastip- 1 y in s. m. a '1 elongations of 33 2 Ultlmate Tune of cure elongaat break tion inlbsJin. 300% 500% minutes at 287F 1233 y 2920 4048 6407 OO-minutes at.287F .1290 r 3105 '--37410 i .580 a The above results show that vulcanization of the stock for one hour at 287 F. gives a full cure for the tread stock shown,, More; over, the stock'is shown to possess desirable commercial properties for a tire tread.

,It has also been found that thoseicompounds containing a piperidyl grouping act as good accelerators for the production of a hard rubber compound. For example, arubber stock comprising 2O parts of --smokedsheet rubber, 20 parts of amber crepe rubber, J7 5 parts of zinc oxide,

10 parts of mineral rubber,

27.5 parts of sulphur, j 7

1 part of phenyl p piperidyl guanidine was cured to produce a characteristic hard rubber upon heating the'compound in a press for approximately two hours at 287 F.

Another example illustrating the wideapplicability of the preferred class of accelera torsin the manufacture of rubber products of different types is shown in the production of acompound containing a high percentage of zinc oxide suitablefor-use as a cushion stock employed in pneumatic'tires or which may be used as a stock for inner tubes for'pneumatic tires fo-rtrucks. Such a stock comprises 100 parts of smoked sheet rubber,

.15 parts of zinc oxide, 7 3.5 parts of sulphur,

05 m of the acceleratorhereinbefore depSCIibed;

' The stock'was prepared in the usual well known manner and Was cured and subjected to physical testing and the following results thereby obtained:

: Loadnecessary to proi duce elongations of I Tensile 1 Time of cure I strength tion at i at break break 45 minutes at 287 F; 220 555 i 1830 3330 8207 60 minutes at 287 F 274 I 660 2510i v.3880 775% p ny to which this invention pertains from a consideration of the various examples hereinbefore set forth.

Since many apparently widely difi'eren embodiments of the invention may be made without departing from the spirit thereof, it is understood that the invention is not limited to the specific examples set forth nor limited nor dependent upon the soundness of any theories herein presented by way of explanation; and although there have been specifically described accelerators that may be utilized in promoting the vulcanization of rubber, it is obvious'that minor changes may be made in 15, the application of the examples of the inventifon without departing from the scope there- 0 What is claimed is: l a

1. The process of manufacturing a vulcanized rubber product which comprises heating a mixture of rubber and sulphur in the presence of an accelerator comprising phenyl-p piperidyl-phenyl guanidine.

2. The process of manufacturing a vulcanized rubber product which comprises heatinga mixture of rubber'and sulphur in the presence of an accelerator. comprising a symmetrical di-aryl substituted guanidine, one of which aryl substituents contains a piperidyl group para toithe imino group. p

3. A vulcanized rubber product comprising the product obtained by heating a mixtureof rubber and sulphur in the presence of a symmetrical di-aryl substituted guanidine accelerator, one of which aryl substituents contains a piperidyl group para to the imino group. 7 v W 4. A vulcanized rubber product comprising the product obtained by heating a mixture 40 of rubber and sulphur in the presence of phenyl-p piperidyl-phenyl' guanidine In testimony whereof I hereunto affixmy signature. c 1

WINFIELD SCOTT. 

